Tycho Brahe was born in Skane (then in
Denmark, now in Sweden) on December 14, 1546, the eldest
of two sons and one daughter born to Otto and Beatte
(Bille) Brahe, both of whom were from noble Danish
families. As per a family agreement, Tycho was adopted by
his paternal uncle, J÷rgen Brahe, who, in April of 1559,
sent him to study philosophy and rhetoric at the
University of Copenhagen. Tycho's studies were
interrupted by the occurrence of a predicted total solar
eclipse on August 21, 1560, however, and from that time
on he was much more interested in astronomy than
philosophy.

Sent to study law at the University of
Leipzig in 1562, Brahe secretly studied astronomy instead
and began continuous observations with a globe, a
pair of compasses and a "cross-staff." He quit
Leipzig on May 17, 1565, but, after the death of his
uncle the next month, went on to the universities of
Wittenberg and then Rostock. At Rostock, a dispute with a
fellow student over a mathematical equation led to a
sword duel, which in turn led to Brahe losing the tip of
his nose; from that time on he wore a metal prosthesis
that has been variously described as being made of either
copper, bronze, gold, or some other metal. He finished
his studies at the University of Augsburg, where he built
a huge quadrant that permitted he and his fellow students
to make extremely precise observations of heavenly
bodies. Matriculating from Augsburg in 1569, Brahe once
again embarked on a "study tour" of Germany,
this time with a focus on chemistry.

Brahe's quadrant at Augsburg

Brahe ended his "study tour" and returned to
the family estate toward the end of 1570 after learning
that his father was seriously ill. After his father died
on May 9, 1571, he was "taken in" by his
maternal uncle, Sterno Belle, who allowed Tycho to build
an observatory at his castle near Knudstrup. There, on
November 11, 1572, he observed a new star in the
constellation Cassiopeia; he published De
Nova et Nullius Aevi Memoria Prius Visa Stella (On
the New and Never Previously Seen Star) the following
year. [Astronomers now know that Brahe actually observed
a supernova, the spectacular explosion of an old star,
not the birth of a new star.]

Brahe's depiction of the 'new star'
he observed

In 1573, Brahe became romantically
involved with Kirsten J°rgensdatter, a peasant girl.
Although the two never formally married, they lived
together as husband and wife until his death. The couple
eventually had eight children, six of whom lived into
adulthood. In 1574, they moved to Copenhagen, where Brahe
spent a year giving a course of lectures at the
university.

After another "study tour" of
Germany in 1575, Brahe accepted an offer from King
Frederick II of Denmark to establish an observatory on
the island of Hveen in the sound between Denmark and
Norway. Built between 1576 and 1580, Uraniborg was the
first building ever designed specifically for
astronomical observations. Brahe personally designed and
built many of the observatory's instruments, took great
pains to calibrate them, and instituted regular nightly
observations of the heavens. He also ran his own printing
press, from which he published De Mundi Aetherei
Recentioribus Phaenomenis (Concerning the New
Phenomena in the Ethereal World) in 1588. This work not
only contained details about a comet he observed in 1577,
but also included his "plan of the cosmos."

drawing of Uraniborg

In Brahe's time, astronomers generally
accepted a theory formulated by Ptolemy 1,400 years earlier -- that the Earth was the
center of the universe, and had no motion. Brahe's
attention to detail in his observations of the 1572 star,
1577 comet, and of planetary orbits led him to easily
dismiss the Ptolemaic system, but he also rejected the
Heliocentric Theory (sun-centered universe) of Nicolas Copernicus. Brahe's "compromise theory" still
placed the Earth at the center of the universe, with the
Sun, Moon, and stars revolving about it, but had all of
the other known planets revolving about the Sun, with the
comet he had discovered in 1577 following a circular path
between the orbits of Venus and Mars.

Brahe's depiction of the universe

In 1597, a dispute with King Christian IV, who
had succeeded Frederick II in 1588, led Brahe to pack up
his books and instruments and leave Denmark. After
spending a couple of years in Germany, he settled in
Prague as Imperial Mathematician in the court of Holy
Roman Emperor Rudolph II. One of the young astronomers
who worked under Brahe in Prague was Johannes Kepler, whose later discovery that planets move in
elliptical orbits was spurred by Brahe's insistence on
observing the Moon and planets throughout their orbits,
not just at important points (apogee, perigee, etc.).

Tycho Brahe contracted a urinary
infection and died unexpectedly on October 24, 1601, and
was buried at Tyn Church in Prague.

Although Brahe's "compromise
theory" of the universe was not universally
accepted, he was still well respected by his
contemporaries. The first astronomer to make corrections
for atmospheric refraction, his observations were
accurate to within 2 arc minutes (some to within about
half an arc minute), at a time when most astronomers were
happy with an accuracy within 15 arc minutes. In addition
to the works already cited, he also published Astronomiae
Instauratae Mechanica (Instruments for the Restored
Astronomy), which included a description of his
instruments, as well as an autobiographical account of
his career and discoveries, in 1598. Astronomiae
Instauratae Progymnasmata (Introductory Exercises
Toward a Restored Astronomy), which discussed the motions
of the Sun and Moon and gave the places of 777 fixed
stars, was edited and published by Kepler in 1602.